I've been trying this out and whilst it seems fun enough, the game really doesn't do a good job of explaining certain things.
Doing the second mission it automatically grouped me with two other players, kinda like how Destiny does on Strike missions. All great, we went through the mission, got it done no problem, back to my ship to install a new segment that unlocks the mod system. While I'm sat going through that, trying to get my head round it, all of a sudden I'm yanked out of my ship and to a mission loading screen with the two players I was with on the previous mission and an additional player.
The game made absolutely zero attempt to tell me that at the end of a mission you need to manually leave a team.
It also didn't tell me how to leave a team, I was left to Google that.